Closing yield gaps
While global demand for food is rising – driven by an increasing population and changing diets – options to convert more land into agricultural use are diminishing, as shown on the previous pages. The only alternative is agricultural intensification, which can be achieved by optimising total farm production and crop productivity (output per land unit). Since actual yields are well-below potential yields in many parts of the world, especially Africa, one of the most widely cited approaches to meeting future food demands is closing the ‘yield gap’ (i.e. actual vs. potential yields per unit area). Associated with this are resource-use efficiency gaps, or differences between actual and potential yields per unit of resource input (e.g. fertiliser, pesticides, water, labour).
In any given area, yield gaps can be a function of many interacting biophysical and socio-economic factors, including water stress and nutrient stress, limited access to markets, low mechanisation, climate (aridity and temperature), soil quality (including steep slopes and poor drainage), undeveloped supporting infrastructure, technical knowledge, credit and uncertain land tenure and labour constraints. Hence, it is not surprising that in spite of its importance, the global potential for agricultural intensification is not very well understood.
During the past 100 years, agricultural intensification has been driven by improved technologies and farming practices, including the use of organic and chemical fertilisers, herbicides and insecticides, development of high-yield crop varieties, improvements in land management and mechanisation and adaption of irrigation. While all of this has led to increased food production, the other side of the coin is that these advances and practices have also led to a higher extraction and consumption of limited natural resources, such as water, forests and nutrients, which in many areas of the globe has led to land degradation. In addition, paradoxically, successful intensification can create economic incentives to bring additional land under cultivation, further increasing pressure on natural resources, especially for less suitable land, which again leads to increased land degradation.
Yield gaps highlight substantial regional differences in agricultural intensity across the globe. The yield gap is closed (or smallest) in industrialised countries with large farm sizes, high fertiliser and pesticide use, sophisticated irrigation technology, improved crop varieties and access to appropriate knowledge. In contrast, yield gaps are typically highest in rural areas of developing countries, mainly in Africa, South America and Asia, where low-input, low-yield smallholder agriculture exists. Attempts to close yield gaps must be tailored to meet local conditions. Many areas with significant yield gaps are dominated by smallholder-based agriculture. These areas, in particular, offer both significant opportunities but also realistic paths to reduce local poverty and improve human well-being. However, agricultural intensification may also lead to adverse affects on natural ecosystems, which will damage ecosystem goods and services critical to the sustainability of rural livelihoods. Development programmes must strike a balance between meeting short-term human needs and long-term environmental impacts. Achieving synergies between food security and global change adaptation and mitigation requires strategies that make smart use of natural ecosystems. New land-management approaches focus on multiple cropping systems to optimise food, fibre and energy production. Mixed with reallocation of crops to more suitable existing croplands not only maximises profits by increased production, but is also more adapted to ecosystem boundaries.
In large part, biophysical factors such as climate, soils and elevation etc., determine global patterns of potential crop yields. But considerable variation in yield can be attributed to other factors, such as land management practices, available technology, farm size, knowledge and available funds for inputs (e.g. irrigation, fertilisers) and crop varieties. Hence, while yields are a useful and important guide to estimate and map potential levels of productivity related to intensification of cultivation, yield gaps represent the potential for improvement. As shown on this page, the ability to map these areas is a valuable tool along with other co-evolving socio-economic and biophysical processes.
The productive capacity of land is often maintained through application of fertilisers to offset what is removed by harvested crops. Where there is an economic and ecological imbalance between input (fertiliser) and output (crop production), pollution can lead to declines in quality and natural resilience of water resources and ecosystems.
Ecological intensification is a knowledge-intensive approach that involves the optimal management of nature’s ecological functions and biodiversity to improve agricultural production2. It is clear that in order to meet the world’s food demand, future cropping systems worldwide must employ this approach by using land, water, biodiversity and nutrients efficiently and in ways that are regenerative and sustainable.
Yield attainment per continent.
Percentage of gridcells with a given yield attainment per continent.
Source: JRC, derived from N. Mueller, 2012.
The significant benefit of closing the yield gap for maize, rice and wheat is illustrated by the amount of future land area at stake that could be gained by closing yield gaps. The ‘current’ (2000) global area of these crops is compared to the total area required to meet 2050 production projections for two cases: (1) if yields remain at their current (2000) levels and (2) if yield gaps are closed.
Source: Redrawn with original data from Phalan, B., 2014.